FIGS. 1 and 2 show a conventional stem for a bicycle which comprises a column member 1 inserted and fixed into the front fork (not shown) and a lateral member 2 pivotally connected to the top of the column member 1 in the manner that the teeth portion 3 at the top of the column 1 is engaged with the teeth portion 4 at the end portion 5 of the lateral member 2 and that a first bolt 6 passes through the hole 7 at the center of the teeth portion 4 of the lateral member 2 and is tightly screwed into the threaded bore 8 at the center of the teeth portion 3 of the column member 1. The angle between the column member 1 and the lateral member 2 can be adjusted by loosening the first bolt 6. However, once the angle is adjusted, the handlebar 9 should consequently be rotatably adjusted by loosening a second bolt 10 so that the gripping portion at free end of the handlebar 9 is comfortably held by a user at an optimal angle and so that the brake lever (not shown) is adjusted to the desired position. Thus, such angle adjustments which involve operating the first and second bolts 6, 10, respectively, are quite troublesome.